This Thing Called Joy

She asked what it is - this thing called 'joy'?

What words might describe it?
Define it?
Explain it?

What is its color?
Its sound?
Its taste? Its smell?

I had no way of answering to the question she'd just asked.

And then - I concluded - there are no words.
This thing called 'joy'?
It's light. It's laughter. It's ephemeral energy. 

It's a moment.
It's a feeling.

It's  this.